Chapter 9 of the USB Specification details some seventeen Standard Device Requests which must be correctly implemented in any USB device, in order for the device to be successfully enumerated by the host controller.

When developing a USB-based device it is a major undertaking to implement the basic Chapter 9 Framework correctly as enumeration will simply fail for any number of reasons involving incorrect responses to the requests.

There is no substitute for a USB bus-analyser for revealing the smallest details of the packet transfers which takes place on the bus. Software based analysers can only ever give you a partial picture of what is going on, usually not reporting at all, the packets with the errors.

The Packet-Master Analyser connects passively between a host computer and the USB device, and captures all USB activity without influencing the link.

Benefits of Packet-Master Bus Analysers

Choice of Investment

The Packet-Master USB12 is a very cost-effective solution to the development of USB low speed or full speed devices. Where the full range of USB speeds is required the Packet-Master USB480+ comes into its own, offering analysis of any speed, revealing the operation of On-the-Go technology hosts. The Packet-Master USB480+ has comprehensive triggering functions and a large FIFO.

Our flagship Packet-Master USB500 AG, provides all the functionality of the USB480+, but can also be configured as a USB Generator. Emulating a host or a device, it allows you to exercise a unit under development in any way you wish. It also features built-in VBUS voltage and current measurement.

Save Development Time

A Packet-Master Bus Analyser will provide you with exact information showing you at which point a device under development is failing. It will save you weeks of wasted development time. In many cases you will find that the error you are looking for is highlighted on the Graphic USB display in a distinctive colour.

Simple Connection

The Packet-Master connects passively between a host computer and the USB device, and captures all USB activity without influencing the link. So you can be sure that you are seeing exactly what really happens. All the important timings are displayed.

Understand USB

When it comes to the USB protocol, a picture is worth a thousand words. The graphical display of Graphic USB immediately provides deeper understanding of the data transfers and their related timings. By examining a working device, you will learn more in a few minutes than from hours of reading the specifications. (Specifications are essential too, but easier to understand when you have a picture in your mind.)

Understand Host Command Sequences

There is no specification as to the sequence of commands which a device may expect from a host. Some command sequences can be very surprising to the starting-out developer. The Packet-Master Bus Analyser will allow you to examine the sequences for any Operating System / Host Controller combination of your choice. This will allow you to reveal any false assumptions you may be making that a particular enumeration sequence is standardised.
(As a device developer, just remember that the device should make no assumptions about enumeration sequences, but simply respond correctly to any request it receives.)

Examine Working Devices

A great benefit available from the Packet-Master Bus Analyser is that it allows you to examine exactly what transactions occur in a working device, perhaps manufactured by a third party. This may reveal your own bad assumptions about how a protocol works, or may show you how many devices on the market do not obey the rules.
Some operating systems have work-arounds for certain common protocol errors, and you may discover some of these first-hand.
Specifications often contain ambiguities. For example, without seeing it for yourself, you might not have realised that there have been two different ways of encoding the version number (bcdUSB) for USB 1.1. Operating systems appear to take the pragmatic approach of accepting either.

Fine-tune Performance

Much of the effort in developing a new device will go into achieving the throughput required. There is no substitute for seeing the transactions attempted by the host, together with the device's response to them. Armed with this valuable information you will be in the best position to be able to fine-tune your device's performance.

Exercise the Device under Development exactly the way you want to

With a Packet-Master Generator, you no longer have to persuade your host computer to produce a rare situation for testing your device. Write a simple script and the generator will do the rest.

Want to know what happens when a transaction occurs which your host never seems to send? Write a script and find out!

USB480+